I have an application that run's on winNT and requires the APCI-7500 card (a 4-multiport serial card), so I've installed the winNT thru virtualbox, but as i try to configure the serial ports I notice that virtualbox shows only 2 serial ports, only 2 tabs in the ports configuration section.

How can I add the other 2 ports and configure them.

My host is ubuntu 11.04
My guest is winNT
My virtualbox version is 4.0.4_OSEr70112

I'll appreciate any help.
Thanks in advance.

I've followed these threads but still get no light in this issue
How to access serial ubuntu host serial port on VirtualBox guest OS
Can't access host serial port on VirtualBox Winxp

3 Answers 3


I'm afraid it looks like you are not going to be able to use that application under VirtualBox:

If your app really requires access to the APCI-7500 card it won't work. VB doesn't emulate PCI devices. It does emulate serial ports, but it just connects them to linux ports.

If you just need lots of serial ports, it won't work. VB only supports up to two serial ports per virtual machine.

There are some workarounds, like tweaking the VB source, or emulating the serial ports with (virtual) usb devices that can work or not in your case.


Not sure about VirtualBox OSE, but if you don't have the serial port options in the settings, then grab the proprietary edition of VirtualBox here.

In the virtual machine settings, you should be able to enable up to two serial ports: enter image description here

It would help if you would share what application you want to use, and what serial port peripheral it requires. Never having used serial port peripherals in a virtual machine myself (and I don't have the hardware to test it), here's the documentation on using this feature.


Don't bother with the emulated ports of the host, forward the APCI-7500 PCI device to the guest, then install its drivers inside Windows.

This should work in all current versions of VirtualBox.

Also consider that host and guest might need to be both the same architecture, e.g. 32-bit.


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